Railway signaling apparatus



Nov.- 5, 1940. o. M. JENSEN 2,220,484

RAILWAY SIGNALING APPARATUS Filed March 25, 1939 9 A 117 6" 7 I E1 21-'L J 2 50% E c 25 c .B

- I 44' 6 m L- 56 INVENTOR 0660 Jensen.

HIS ATTORNEY Patented Nov. 5, 1940 UNITED STATES PATENT OFFICE Otto M.Jensen, Milwaukee, Wis., assignor to The Union Switch & Signal Company,Swissvale,

Pa., a corporation of Pennsylvania Application March 25, 1939, SerialNo. 264,181

4 Claims.

My invention relates to railway signaling apparatus, and particularly toapparatus for the control of highway crossing signals.

A feature of my invention is the provision of 5 novel and improved meansfor checking a track circuit used to govern a signal control circuit.

A further feature of my invention is the provision of novel and improvedmeans for controlling a time element device associated with a trackcircuit used to govern a warning operation of a highway crossing signalin response to a train occupying the track circuit, the time elementdevice being eifective to discontinue such warning operation of thesignal a predetermined time interval subsequently to the train occupyingthe track circuit. Other objects and advantages of apparatusembodying'my invention will appear as the specification progresses.

I shall describe one form of apparatus embodying my invention, and shallthen point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic View of a preferred form ofapparatus embodying my invention.

Referring to the drawing, the reference characters la and lb designatethe track rails of a stretch of railway over which trafiic normallymoves in the direction indicated by an arrow, and which railway isintersected at grade by a highway H, a highway crossing signal S beinglocated at the intersection. The signal S may be any of the severalwell-known types and as here shown is an audible signal in the form ofan electric bell.

The track rails la and intersection lfrom which traffic normallyapproaches the highway are formed by the usual insulated rail jointsinto two track sections DE and EF, a train traversing these tracksections in the order named when approaching the intersection and theexit end of section EF being preferably located adjacent the highway. Ishall call the section DE a first or normal operating section and thesection EF a second or emergency operating section. The section EFwould, ordinarily at least, be relatively short and of just sufiicientlength to provide a desired period of warning operation of the signal Sprior to the arrival of a train at the intersection when the trainoperates at a relatively low speed, and such warning operation isinitiated when this low speed train first enters the section EF. Thesection DE is preferably of sufficient length so that section DE and theshorter section E-F providea desired period of the warning operation lbon the side of the of the signal S prior to the arrival of the train Iat the intersection when the train traverses the two sections at themaximum permissible speed for all trains, the warning operation in thislatter case being initiated when the train enters section DE and beingcontinued of course while the train occupies section EF.

Specifically, such a track layout would be used where track section DEincludes track switches leading to spur tracks or where a station islocated adjacent the section. Hence some trains at least would occupysection DE for a relatively long period of time in switching or standingat the station.

Each of the track sections D--E and E F is provided with a trackcircuit. section DE, the normal track circuit includes a track battery 3connected across the track rails at the entrance end of the sectionthrough a current limiting resistor 4, and a direct current track relay2 whose operating winding 5 is connected across the rails of the exitend of the section over lead wires 6 and I, an impedance or reactanceunit 8 being interposed in the lead wire 6. The section DE is alsoprovided with an auxiliary or checking track circuit which in- I cludesa source of alternating current such, for example, as a tracktransformer 9, an alternating current track relay Ill, and two resistorsll and I2. As here shown, the primary winding l3 of transformer 9 hasits two terminals BX and CX supplied with alternating current from anyconvenient source such as a generator not shown. The secondary windingId of transformer 9 and the operating winding l5 of relay l0 areseriallyconnected across the rails at the exit end of section DE by virtue of acircuit one side of which circuit can be traced from the left-handterminal of secondary winding l4 over wire l6, resistor H, and lead wireI to rail lb; and the other side of which circuit can be traced from theright-hand terminal of secondary winding l4 over wire l'l, operatingwinding l5 of relay l0, wire l8, resistor l2, and lead wire 6 to railla.

Normally, that is, when section D--E is unoccupied, the direct currentrelay 2 is effectively energized and picked up by the direct currentsupplied from the track battery 3, the impedance unit 8 ofiering butlittle resistance to the flow of direct current but being soproportioned as to I li In the case of substantially block the flow ofalternating cur rent from the transformer 9 to the operating winding 5of relay 2. Under this unoccupied condition of section DE, thealternating current flowing in the operating winding l5 of relay ll] isonly the leakage current passing between the track rails due to theballast resistance, the connection at battery 3 and the path throughwinding 5 of relay 2 and unit 8. This leakage current may or may not besuificient to energize relay I8 sufficiently to pick up the relay. Aswill shortly appear, it is immaterial whether or not the relay I8 ispicked up when the section DE is unoccupied. In the drawing the relay I8is illustrated as being released under the unoccupied condition ofsection DE. The resistors II and I2 are proportioned so that littledirect current from battery 3 flows through the auxiliary circuitincluding the secondary winding I4 of transformer 9 and the operatingwinding I5 of relay I0 and hence this auxiliary circuit does not form ashunt path to relay 2 that materially affects the operation of relay 2.

When the track section DE is occupied by a train the track relay 2 isshunted and released in the usual manner. The additional alternatingcurrent caused to fiow due to the low train shunt resistance between thetrack rails efiectively energizes the alternating current relay I8 andthat relay is picked up. The manner by which this operation of thealternating current track relay I8 is used to check the operation of thenormal direct current track circuit will appear hereinafter.

The track section EF is provided with a direct current track circuitincluding a track battery I9 and a direct current track relay 28, therelay 28 being connected across the rails at the exit end of sectionE--F as will readily appear by an inspection of the drawing. The trackbattery I9 is connected across the rails of the section EF over twoalternative paths. To be explicit, one terminal of battery I9 isconnected with the rail lb over a lead wire 2|, and the other terminalof battery I9 is connected with the rail Ia over two alternative paths,one path including a current limiting resistance 22, front contacts 23and 24 of relay 2 in multiple and lead wire 25. The other path includesresistor 22, wire 41, front contacts 26 and 21 in multiple of a relay 28to be referred to later, and lead wire 25.

It follows that when section E-F is unoccupied the relay 28 is energizedand picked up when either the track relay 2 of section DE is picked upclosing front contacts 23 and 24, or when the relay 28 is picked upclosing front contacts 26 and 21. When the track section EF is occupiedby a train the relay 2!) is shunted in the usual manner irrespective ofthe condition of the relays 2 and 28.

The signal S is provided with a simple operating circuit easily tracedand which includes a back contact 29 of a normally energized controlrelay 30 so that signal S is normally silent and is sounded to provide awarning operation when the relay 38 is deenergized. The relay 30 isnormally energized over either one of two alternative circuits, onecircuit extending from terminal B of a convenient source of directcurrent such as a battery not shown, front contact 3| of track relay 2,wire 32, front contact 33 of track relay 28, winding of relay 3!] and toterminal C. The other circuit extends from terminal B of the currentsource over back contact 34 and contact finger 36 of a thermal relay THto be shortly described, wires 35 and 32, front contact 33 of trackrelay 28, winding of relay 30 and to terminal C.

The apparatus also includes a time element device here shown as athermal relay TH and a stick relay 28. The type of thermal relay TH isimmaterial and it may be any one of several of the well-known types. Itis deemed sufficient for this application to say that relay TH isprovided with a heater element 38 and two circuit controlling contactfingers 36 and. 31, the contact fingers being insulated from each otherbut mechanically connected as indicated by a dotted line so that the twomove substantially in unison. When the heater element 38 is cold the twocontact fingers 36 and 31 occupy the position illustrated in the drawingwith contact finger 38 in engagement with the back or checking contact34 and the contact finger 31 disengaged from the front contact 39. Whenthe heater element 38 is supplied with heating current for apredetermined time interval, say for example 20 seconds, the contactfingers 36 and 31 are moved so that contact finger 38 is disengaged fromback contact 34 and the contact finger 31 engages the front contact 39.When heating current is removed from the heating element 38 the heatingelement quickly cools and the contact fingers 36 and 31 are moved backto their normal positions, that is the positions illustrated in thedrawing.

The relay TH is provided with a control or heating circuit which extendsfrom terminal B over front contact 40 of relay I0, back contact M ofrelay 2, wire 44, back contact 42 of relay 28,

back contact 43 of relay 20, heater element 38 f and to terminal C. Itis to be observed that this control or heating circuit is closed onlywhen the alternating current relay I8 is picked up closing front contact40, and the direct current track relays 2 and 20 are released closingback contacts 4| and 43, respectively.

The stick relay 28 is provided with a pick-up circuit that extends fromterminal B over front contact 40 of relay I 8, back contact 4| of relay2, wires 44 and 45, front contact 39 and contact finger 31 of thermalrelay TH, winding of relay 28 and to terminal C. With relay 28 oncepicked up it is retained energized over a stick circuit that is the sameas its pick-up circuit up to wire 44 and thence over front contact 46and winding current track relay 2 is shunted and is released 3'5 but thealternating current relay I8 is energized at its pickup value by virtueof the train shunt, and this latter relay is thus picked up. With trackrelay 2 releasing to open front contacts 23 and 24 the first tracedalternative path for conm necting track battery I9 with the rails ofsection E'-F is opened and hence track relay 28 is in turn alsodeenergized and released opening front contact 33 and closing backcontact 43 due to the second alternative path being also open.

Since front contact 33 of track relay 28 is interposed in both circuitsfor the control relay 30, the relay 30 is deenergized and released toclose back contact 29 with the result that the warning operation of thesignal S is initiated. With both 1 track relays 2 and 28 releasedclosing back contacts 4| and 43, respectively, and the alternatingcurrent relay I0 picked up closing front contact 40, the heating circuitfor the thermal relay 'I'H is completed with the result that the relayTH is heated and operates its contact fingers 36 and 31 after thepredetermined operating time of relay TH. The operation of contactfingers 36 and 31 opens back contact 34 and closes front contact 39 ofrelay TH. As soon as the front contact 39 is closed the pick-up circuitfor relay 28 is completed and'that relay is picked up and then retainedenergized over its stick circuit. With the picking up of relay 28closing front contacts 25 and 21 the alternative path for connecting thetrack battery l9 across the rails of section E--F is completed with theresult that the track relay 2!) is again energized and picked up sincethe train is still in the section DE and the section EF is unoccupied.When relay 28 picks up opening back contact 42 the heating circuit forrelay TH is opened and the heater element 38 of that relay is cooled sothat its contact fingers 36 and 31 shortly move back to their normalpositions. The closing of back contact 34 of the thermal relay THcompletes the second one of the control circuits for relay 30 sincetrack relay 20 is now picked up closing front contact 33 and relay 30 onpicking up opens the operating circuit for signal S and the warningoperation of the signal ceases. The signal S now remains silent as longas the train remains in the section DE.

When the train in section DE has completed its work and again movesforward toward the right, it will enter section EF at a relatively lowspeed. When the train enters the section EF and shunts track relay 20,the release of that relay opens front contact 33 and brings about thewarning operation of the signal in the manner previously explained. Thewarning operation of the signal S prior to the arrival of the train atthe intersection will be of sufiicient interval to assure safety for thehighway users because the train speed is relatively low. When the trainpasses over the intersection to the right and vacates section EF, thetrackrelay 20 is reenergized and picked up because the track relay 2 ofthe section DE is picked up when the train vacates section DE. With bothtrack relays 2 and 20 picked up, the control relay 30 is reenergized andthe warning operation of the signal ceases.

In the event a train moving at the usual speed approaches the highwayfrom the left and passes through the track sections DE and EF withoutstopping, the warning operation of the signal S is initiated as soon asthe train enters the section DE and shunts track relay 2 and the warningoperation of the signal is then continued without interruption until thetrain passes over the intersection and vacates the section E--F becausethis train will pass through the section DE before the thermal relay THhas had time tocomplete its operation.

In the event the normal or direct current track circuit of section DEshould fail due to a weakened track battery, or broken rail bond, orbroken rail, or other loss of power, the release of track relay 2 toopen front contacts 23 and 24 will disconnect the track battery I9 fromthe section EF and track relay 2!! will be deenergized and released withthe result that the warning operation of the signal S is initiated. Suchfailure of the track circuit for section DE will tend to decrease theflow of alternating current so that the alternating current relay I!)will be deenergized. With relay [0 not picked up to close its frontcontact 40, the control or heating circuit for the thermal relay THremains open after the track relay 2 is released and hence the timeelement device does not function to bring about an interruption of thewarning operation of the signal S after a predetermined time. Heretoforewhen such time element devices have been provided with track circuitsthat govern the operation of a highway crossing signal a failure of thetrack circuit which causes a release of the track relay will initiatethe operation of the signal and also cause operation of the time elementdevice so that the warning operation of the signal is interrupted at theend of the predetermined time interval for the operation of the timeelement device. In such case, when a train next approaches the highwaythe warning operation of the signal is not initiated for that trainuntil the train enters the emergency track section and the warmingoperation prior to arrival of the train at the intersection may be of soshort a duration that it is oflittle use in protecting the highwayusers. It is to be seen, therefore, that with apparatus embodying myinvention the superimposing of alternating current on the normal directcurrent track circuit provides a control for the time element devicesuch that the time element device is rendered ineffective to discontinuethe operation of the highway crossing signal when the track relay isdeenergi'zed due to a failure of the track circuit. In other words, withapparatus embodying my invention, the thermal relay or time elementdevice is effective to interrupt the operation of a highway crossingsignal only when the track circuit is occupied by a train.

It will be understood, of course, that my invention is not limited tothis one application but that this one use of apparatus embodying myinvention will serve to illustrate the many places where the apparatusmay be used.

Although I have herein shown and described only one form of railwaysignaling apparatus em- 4!) bodying my invention, it is understood thatvarious changes and modifications may be made therein within the scopeof the appended claims without departing from the spirit and scope of myinvention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a highway,a highway crossing signal located at said intersection, a track sectionformed on one side of said intersection, a track circuit for saidsection including a source of direct current and a direct current trackrelay connected across the rails at opposite ends of the section tonormally energize said relay and to shunt said relay when a trainoccupies the section,

a source of alternating current, an alternating current relay, means toserially connect said source of alternating current and said alternatingcurrent relay across the rails of the section at the,

same end said direct current track relay is connected across the railsto energize said alternating current relay when a train occupiesthesection, an operating circuit controlled by said direct current trackrelay when shunted to cause operation of said signal, a time elementdevice, means governed by said device when operated a predetermined timeinterval to remove said operating circuit from the control of saiddirect current relay, and a control circuit for said device seriallyincluding a front contact of said alternating track relay and a backcontact of said direct current track relay.

2. In combination, a stretch of railway track intersected by a highway,a highway crossing signal located at the intersection, a first and asec-. ond track section formed on one side of the intersection andtraversed in the order named by a train approaching said highway, atrack circuit for each of said sections, said track circuits eachincluding a source of direct current connected across the rails at oneend of the associated section and a direct current relay connectedacross the rails at the other end of the associated section, a frontcontact of the track relay of said first section interposed in theconnection of the current source of the second section, a controlcircuit including a front contact of the relay for said second sectionfor governing the operation of said signal, a time element deviceoperative when energized a predetermined period to establish a shuntpath for the connection of the current source of the second sectionaround said front contact of the track relay of the first section, asource of alternating current, an alternating current relay, means toserially connect said source of alternating current and said alternatingcurrent relay across the rails of said first section to energize thatrelay when a train occupies said first section, and an energizingcircuit for said device serially including a front contact of saidalternating current relay and a back contact of the direct current relayof said first section.

3. In combination, a stretch of railway track intersected by a highway,a highway crossing signal located at the intersection, a first and asecond track section formed on one side of the intersection and,traversed in the order named by a train approaching said highway, atrack circuit for each of said sections, each of said track circuitsincluding a source of current connected across the rails at one end ofthe section and a track relay connected across the rails at the otherend of the section, a front contact of the track relay for said firstsection interposed in the connection of the current source for thesecond section, a control circuit including a front contact of the trackrelay for said second section for governing the operation of saidsignal, a time element device operative When energized a predeterminedtime interval to establish a shunt path for the connection of thecurrent source for the second section around said front contact of thetrack relay for the first section, another track circuit including therails of the first section and a track relay connected to the rails tobe picked up when the rails are shunted, and an energizing circuitincluding a front contact of the track relay of said other track circuitto energize said device.

4. In combination, a stretch of railway track intersected by a highway,a highway crossing signal located at the intersection, a first and asecond track section formed on one side of the intersection andtraversed in the order named by a train approaching said highway, atrack circuit for each of said sections, each of said track circuitsincluding a source of current connected across the rails at one end ofthe section and a track relay connected across the rails at the otherend of the section, means including a front contact of-the track relayfor the first section to interrupt the track circuit of the secondsection when the track relay for the first section is released, acontrol circuit including a front contact of the track relay for thesecond section for governing the operation of .said signal, a timeelement device having a normally open contact which becomes closed whenthe device is energized a predetermined time interval, means includingsaid contact of the time element device when closed to close the trackcircuit of said second section when the trackrelay for the first sectionis released, an auxiliarytrack relay and a current source connected inseries across the rails of said first section to pick up-such auxiliaryrelay when the rails of that section are shunted, and a circuitincluding a front contact of said auxiliary relay and a back-contact ofthe track relay for the second section to energize said time elementdevice.

' OTTO M. JENSEN.

